ACCESS 39, Fall 2011

During the last half of the 20th century, cities and towns across America were built primarily for one transportation mode: the automobile. Much of this development occurred on the urban periphery, creating the suburbs that are now home to more Americans than either traditional central cities or small towns. Today, while federal transportation policies and urban planners have shifted toward promoting a more multimodal form of development, the legacy of the postwar era remains: thousands of suburban neighborhoods poorly served by any mode of transportation other than the automobile.

The effectiveness of transportation policies will depend on how users respond to them. Therefore, we must understand how to predict and influence behavior over the long term, which is the realm of travel demand modeling.

Pick a city, any city in the US, and then pick a house within that city. Open the door of its garage and you're likely to find a bicycle. Chances are good that it is covered with dust or has a flat tire. If not, and if its owner has in fact used it any time recently, odds are the purpose was exercise or recreation. Compare this to a garage, any garage, in Davis, California. Inside you're likely to find several bicycles—more bicycles, perhaps, than people living in that house. In all probability, one or more of those bicycles is used at least weekly, not for exercise or recreation but for transportation—to get the rider to work, school, the store, a restaurant, or another destination in town.

Bikesharing has evolved greatly since the first program was launched in the Netherlands in the mid-1960s. As of May 2011, there were an estimated 136 bikesharing programs in 165 cities around the world, with 237,000 bikes on the streets. In the Americas, bikesharing activity has spread to Canada, Mexico, the US, Argentina, Brazil, and Chile. Asia, which represents the fastest-growing bikesharing market today, has programs in China, South Korea, and Taiwan.

We know surprisingly little about how parking infrastructure affects energy demand, the environment, and the social cost of vehicle travel. Passenger and freight movements are often the focus of energy and environmental assessments, but vehicles spend most of their lives parked. Because abundant free parking encourages solo driving and thus discourages walking, biking, and the use of public transit, it greatly contributes to urban congestion. The environmental impacts of parking and the driving it promotes are often borne by local populations and not the trip-takers themselves.

Almost everyone can tell an anecdote about disabled placard abuse. One of mine stems from a visit to the Capitol building in Sacramento. After noticing that cars with disabled placards occupied almost all the metered curb spaces surrounding the Capitol, I talked to one of the state troopers guarding a driveway entrance. He watched all the arrivals and departures at the nearby metered spaces every day. When I asked the trooper to estimate how many of the placards he thought were being used illegally, he responded, "All of them."